N222-116 TITLE: Tunable, Repeatable, Calcium Lanthanum Sulfide Ceramic Powder Development

OUSD (R&E) MODERNIZATION PRIORITY: General Warfighting Requirements (GWR);Hypersonics

TECHNOLOGY AREA(S): Materials / Processes;Sensors; Weapons

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws.

OBJECTIVE: Develop a process to manufacture Calcium Lanthanum Sulfide (CLS) powder suitable to provide a starting material for producing optical ceramics.

DESCRIPTION: Since the 1970’s sulfides of the general formula AB2S4 have been considered as possible optical materials. Work in the 1980’s done in the United States and Great Britain specifically considered applications for CaLa2S4 as an infrared transparent aperture material [Ref 1]. At that time, the difficulty that has inhibited the development of CLS as an optical ceramic material was stated as: "Reproducibility of the product remains a problem, which is thought to be a result of variability of the powder. However, measurable properties of the powder which can be used to predict if a particular batch of powder will give a good ceramic piece have been impossible to identify." [Ref 2]

Current interest in CLS is motivated by the desire to (a) revisit basic research investigations into its high temperature optical and mechanical properties [Ref 3], and (b) to perform applied research into its application as a material for multi-band optical components with complementary chromatic dispersions [Ref 4]. The literature has a number of reported synthetic processes, but typically these are at a TRL2/MRL2 laboratory proof of concept level. It is the goal of this SBIR topic to mature a CLS optical ceramic powder-manufacturing process to TRL4/MRL4. This level of maturity should encompass providing both highly consistent CLS powder for an Acquisition Program of Record and providing the capability for tuning the CLS powder for basic research [Refs 5, 6].

The CLS powder-manufacturing process must lead to consistent powder properties across multiple lots of powder delivered, with well-understood powder characterization metrics linked to optical and mechanical performance of fully dense coupons and optical component prototypes. The CLS powder-manufacturing process must also be tunable allowing for the controlled variation of powder stoichiometry and physical characteristics to permit the refinement of the optical and mechanical properties of fully dense coupons and component prototypes. The fabrication of fully dense coupons and component prototypes is outside the scope of this SBIR topic, but powder manufacturers shall work with third party fabricators to exchange technical information that will lead to an evaluation of the repeatability and tunability of delivered powder lots.

PHASE I: Develop and/or demonstrate method(s) for synthesizing high purity CLS powder that is suitable for densification to maximize optical performance. Develop powder characterization metrics and measurement procedures for attributes such as stoichiometric composition, particle size and morphology, rheological properties, etc. Demonstrate the relation between intended Ca:La stoichiometry and measured stoichiometry and any replacement of sulfur by oxygen. Demonstrate the repeatability of obtaining an intended stoichiometry. Collaborate with a third party participant who will produce fully dense optical coupons/parts from the synthesized powders. Deliver to the Government (1) an initial minimum 50g sample powder, at a date within the Phase I period of performance (PoP) as projected by the proposer and (2) a single lot of 500g powder at the end of the Phase I PoP. These powder deliveries will be used by the Government to support third party coupon fabrication and subsequent material characterization and testing. Participate in a kick-off meeting at the Central Florida Tech Grove in Orlando, Florida [Ref 7] and in regular monthly telecons, which could bring together one or more third parties in addition to the Government and could include other optical industry fabrication and finishing houses, optical system design and manufacturing companies, as well as university and Government lab participants. Schedule a meeting at the end of Phase I, to include a tour of the powder manufacturing facility. Deliver a rough order of magnitude cost estimate for a notional, but viable, scale-up plan of the process to (a) 5 kg/month and (b) 50 kg/month capacity, noting any capital equipment costs, monthly labor costs, and a quality control plan for key powder metrics that document the repeatability of powder properties. Prepare a Phase II plan.

PHASE II: Participate in a Phase II kick-off meeting at the Central Florida Tech Grove in Orlando, Florida [Ref 7] and participate in regular monthly telecons, which could bring together one or more third parties in addition to the Government. These meetings and telecons could include other optical industry fabrication and finishing houses, optical system design and manufacturing companies, as well as university and Government lab participants. Modify CLS powder attribute metrics to meet needs of third party coupon/part fabricator based on meeting/teleconference outcomes, including quantification of Ca:La stoichiometry and efforts to quantify oxygen content within the sulfide. Deliver to the Government two 500 g lots (with modified metrics if required) to demonstrate tunability of the process. Subsequently to demonstrate repeatability of process control, deliver to the Government four 500 g lots with consistent, agreed upon, powder attribute metrics, based on the prior two 500 g lots.

PHASE III DUAL USE APPLICATIONS: Potential dual use applications may include optical windows on infrared sensing equipment, supporting optical components for various infrared lasers on medical equipment. Could also lead to further miniaturization of forward-looking infrared cameras for manufacturing advancements. Material may also be considered as a durable replacement material for zinc sulfide.

In partnership with a commercial or Government program, tune the powder metric attributes and scale-up repeatable CLS optical ceramic powder production to support the manufacture of prototype and commercial optical components.

REFERENCES:

1. Saunders, Kenneth J.; and Tustison, Randal.W. "Process for Making an Optically Transmissive Body." U.S. Patent 4,619,792, Jun. 3, 1983. http://patft.uspto.gov/netahtml/PTO/search-bool.html
2. Hills, Marian E. "Preparation, Properties, and Development of Calcium Lanthanum Sulfide as an 8- to 12 -micrometer Transmitting Ceramic." NWC TP 7037, September 1989. https://apps.dtic.mil/dtic/tr/fulltext/u2/a220200.pdf
3. Koenig, J. R. "Thermal and Mechanical Properties of Calcium Lanthanum Sulfide" , Final Report to Office of Naval Research, Contract number NO014-83-K-0195, April, 1985. https://apps.dtic.mil/sti/pdfs/ADA160611.pdf
4. "Dual-Band Lens SWAP Reduction and Increased Optical Throughput with Calcium Lanthanum Sulphide (CLS)." Army SBIR Topic A20-050, 2020.1. https://www.sbir.gov/node/1654403
5. "DoD Manufacturing Readiness Level Deskbook – Aug 2015." http://www.dodmrl.com/MRL_Deskbook_V2.4%20August_2015.pdf
6. "Technology Readiness Assessment Deskbook; Appendix C – July 2009." https://apps.dtic.mil/dtic/tr/fulltext/u2/a554900.pdf
7. Central Florida Tech Grove https://www.centralfloridatechgrove.org/

KEYWORDS: optical material; ceramic; powder; Long Wavelength Infrared; LWIR; Calcium Lanthanum Sulfide; CLS; high temperature material